In some chemical process operations closed reactor vessels are used to contain reagents that are to react under substantial pressure. The interior of the vessel is accessible through a relatively large opening which is closed by a main hatch during operation. Sensors inside the vessel are usually arranged to provide indications at some exterior location of operating conditions such as temperature and pressure. Generally, some provision is made for giving an alarm or emergency signal when the internal pressure, for example, becomes excessive.
The sensor outputs and/or emergency signal may be monitored by a human operator, or in some instances by a computer, to take appropriate measures such as turning off a heater when the reactor pressure begins to build up. However, in some cases the pressure can increase much too suddenly to be counteracted in such manner, or by conventional safety valve systems. In such event, the reactor may explode, destroying itself and damaging its environment.